This invention is directed to a fade control circuit for use with an auxiliary amplifier, which allows power distribution to the auxiliary amplifier to be varied automatically in unison with power distribution to front speakers included in a sound reproduction system.
In modern automotive sound reproduction systems it is often desirable to use a main amplifier to drive front and rear main loudspeakers, and an auxiliary amplifier to drive an auxiliary rear speaker. Such systems have the advantage of increased power and reduced distortion as compared with commonly available single amplifier systems. It is also conventional to provide a fader control to control the distribution of power between the front and rear main speakers. The fader control can be used to balance the loudness of the front main speaker with respect to the rear main speaker to achieve the desired power distribution.
However, in the past it has been common practice to run the auxiliary amplifier and the auxiliary rear speaker at a power distribution which is independent of the setting of the fader control. Such an arrangement provides the disadvantage that the loudness of the auxiliary speaker can serve to reduce the effective range of adjustability of the front-rear loudness ratio, in that the loudness of the auxiliary rear speaker is not adjusted by the fader control. Thus, power distribution to the auxiliary rear speaker can effectively prevent extremely high front to rear power ratios.